There have now been over fifty Eurovision Song Contests, since the first event staged in the Swiss city of Lugano on Thursday 24th May 1956. There were only seven competing nations on that occasion, and uniquely each country had two songs in the competition, and the voting was kept private, with only the winner being announced. The 1957 and 1958 contests each had ten competing songs, making them the smallest contests. With more countries joining the competition since 1993, a system of relegation was introduced to limit the number at each contest. In 2004 a new semi-final system was introduced, which allowed all interested countries take part in the contest. In 2008 there will be another change to the format of the contest with two semi-finals, with ten entries advancing to the final, where they will join five automatic finalists.
Selection procedures

Each country must submit one song to represent them in any given year they participate. The only exception to this was when each country submitted two songs in the inaugural Contest. There is a rule which forbids any song being entered which has been previously commercially released or broadcast in public before a certain date relative to the Contest in question.

Countries may select their songs by any means, whether by an internal decision of the participating broadcaster or a public contest that allows the country's public to televote between several songs. The EBU encourages broadcasters to use the latter, as this generates more publicity for the contest. These public selections are known as national finals.

Some countries' national finals are as big as—if not bigger than—the international Eurovision Song Contest itself, involving many songs being submitted to national semi-finals.The Swedish national final, Melodifestivalen (literally, "The Song Festival") includes 32 songs being performed over four semi-finals, played to huge audiences in arenas around the country, before the final show in Stockholm. This has become the most-watched programme of the year in Sweden. In Spain, the reality show Operación Triunfo started in 2002; the winners of the first three seasons proceeded to represent the country at Eurovision.

Regardless of the method used to select the entry, the song's details must be finalised and submitted to the EBU before a deadline some weeks before the international Contest.

Since 1971, each participating country has been required to provide a preview video of their entry, ostensibly to be broadcast in all the nations taking part. Broadcast of the previews was compulsory until the mid 1990s, but is no longer so, providing each country provides access to the videos online.